I cant add loop cuts
press Shift+A and add a lattice

after that, select the object to be deformed and add a lattice modifier
 Under the modifier, make sure you select the lattice as the object  select your lattice, and go to edit mode, pressing TAB key; press Shift+leftclick to select the 4 vertices on the -Y direction of the lattice, press S to scale them. I've uploaded your blend file with the lattice: